Noiseless device



Feb. 16, 1937. H. l.. ADAMS 2,071,012l

-NOISELESS DEVICE Filed Nov. 22, 1932 2 Sheets-Sheet l Feb. 16, 1937. H,ADAMS NOISELESS DEVICE Filed Nov. 22, 1952" 2 Sheets-Sheet 2 ?atentedFeb. 16, y1937 UNITED STATES PATENT OFFICE 6 Claims.

This case is a continuation in part of my original application SerialNumber 461,412, nled April 14, 1921, and since matured into PatentNumber 1,888,418.

My invention primarily relates to that class of flying machines whichare heavier than air but certain details may be used on any nyingmachine, aircraft, or other uses.

The object of Amy invention is to provide a nexible material at the rearedge of fast moving objects or fast moving parts tol reduce the noisecaused by the inrush of air after the object or parts has moved on.

A further object is to provide nexible parts attached to moving orvibrating parts which produce noise to decrease or eliminate the noise.

A still further object is to provide a noiseless device that may bebrought into operation or removed from operation when the need or lackof it exists as when an aeroplane may be making a surprise attack uponan enemy, or when near thickly settled communities where noise isobjectionable, at other times for enlciency it may be removed.

A still further object is to provide flexible material at any place todecrease noise substantially as shown or disclosed.

A still further object is to provide means in an aircraft similar tothose employed by some of the most noiseless night birds, especially theowl that has soft, downy feathers in connection with its wings. The owlbeing an ornithopter requires this device in dinerent location. than agliding motion would require. Nevertheless, the owl in its plunge afterits prey glides to some extent.

A still further object is to provide a device to reproduce in mechanicalform the wings of an owl which is known to be a bird whose night isswift' and most noiseless having soft downy feathers in connection withthe under side thereof. feathers common to most birds.

A still further object is to provide a device of the kind described,which, while primarily intended for aircrafts, may be adapted for use inconnection with any vehicle or device.

Also there are certain other advantages which will hereinafter appear.

To these ends my invention consists in certain fw novel features which Iwill now proceed to describe and will then particularly point out in theclaims.-

In the accompanying drawings Figure 1 is a fragmentary plan of noiselessdevice.

Figure 2 is a cross section through Figure 1 This is entirely apart fromregular bird showing the noiseless device attached to means forwithdrawing or extending said noiseless devicei'rom or to operation.Figure 3 is a perspective cross section of an aerofoil .for an aeroplanewing showing the at- 5- tachment of flexible material to make silentnight by breaking up the eddies or vibration of air that cause sound.

Figure 4 is a perspective detail of a means for securing flexiblematerial in an aerofoil. Figure 5 shows a'perspective sectional view ofa hollow strut or brace or framing with flexible material attached forreducing noise of night or vibration.

Figure 6 shows a detail of the hub of a pro- 15 peller with a preferredmethod of clamping the lines in the propeller to reduce the noise.

Figure 7 is amore complete view of propeller with noise reducing-linesshown attached to the trailing edge of the propeller. 2o

Figure Sis a cross section through a propeller bla-de and hub showing anautomatic means or a means for operating the silencing device of thepropeller while in night.

`In illustrating this device more specincally, I 25 show noise reducingelements in the form of nbres I which may be attached to and extendedfrom any element 2 which constitutes an airfoil. The nbres I arepreferably of elongated form, and of limber construction in order thatthe out- 3 ermost portions thereof may extend within the airstream ofthe airfoil in a, somewhat parallel relation to the part of theairstream in which they move. The fibres may be secured to a movableheader 4 within a slide joint 3, having means 35 for controlling,extending or removing nbre or they may be immovably secured in place,such as by means of a cleat 5 and bolts 6. In addition to providing thenbres at the trailing edge of the airfoil or part with which they areused, the nbres 40 also may be provided at various points along thesurface of the airfoil as shown in Figure 3. Preferably the nbres I willbe in the form of lengths of rope of relatively soft or nuify material,and may be secured at their inner ends as shown in Fig- 45.

ures 3 to 5, or may be extended inwardly beyond their points ofconnection as shown at 1 in Figure 2l in order that such extensions maybe utilized for drawing in or letting out any movable part such as theheader 4 to which the nbres may be 50 connected. The extensions 'I maybe secured in any suitable manner within reach of the aviator. Specincmeans for adjusting the exposed lengths of the nbres I are showninvFigure 8, wherein the airfoil 2c represents a hollowpropeller v55 ber2| having a compressed iluid supply pipe 22 discharging thereinto. Apiston Il is slidable within the chamber 2l, and is connected with theinner end of the airioil or propeller blade 2c in 'order that the lattermay bev retracted by the application oi' pressure within the chamber 2i,or may be permitted to extend by the action of 'centriiugal force uponlowering or discontinuing such pressure.

'In order that the nbres I may be automatically controlled by theextension and retraction of the blade 2c, the header 4a to which theilbres are.

secured is connected bygmeans of a plurality of and extending into theinterior of the hollow blade 2c. The lines 1a pass over pulleys i whichchange the direction oi' the lines and operate to draw the header 4ainwardly upon the extension of the blade 2c. The header la is disposedadjacent a suitable opening I0 in the blade 2c, and is maintained inproper relation therewith to have the nbres I extend therethrough bymeans of projections II on the header 4m which slidably extend throughguides I2 immovably secured within the blade 2c. If desired, the linesla may beextended to any suitable manually controlled operatingmechanism located at any convenient place within reach of the aviator.Any movement of the header la toward or from the opening I 0 willlengthen or shorten the projecting portions of the bres I. v

I have shown an apparatus embodying my in vention in several generalforms but do not wish to be understood as limiting myself strictly tothe precise details of construction herein before described. I do notwish to be held to exact shapes or dimensions or to any particularcombination o! parts but wish to be free to use any part herein ordescribed or covered by the class with any other parts or part whethershown herein or elsewhere.

Having thus described my invention, what I claim as new, and desire tosecure by letters Patent issl. In a flying machine, an air contactingpart. noise reducing means secured to said part, said noise reducingmeans comprising napping members in connection with said part, and meansto extend and withdraw said napping members.

2. In a ilying machine, an airfoil, noise reducing means secured to saidairioil, said noise reducing means comprising nbrous material inelongated form, one end ot which is secured to said airfoil, andautomatic means to adjust the exposed lensth of said brous material. 3.In a flying machine, an airfoil, noise reducin`g means secured to saidairioil, said noise reducing means comprising iluiiymaterial inelongated -form, one end of which is secured to said airfoil, and meansto adjust the exposed length of said uiIy material into operativeandinoperative position.

4. In a ying machine, an air'foil, noise reducing means secured to saidairi'oil, said noise reducing means comprising fibrous material inelongated Iorm, one end o1' which is secured tosaid airi'oil. and meansto adjust the exposed length of said nbrous material.

5. In a flying machine, an airi'oil, noise reducing means secured tosaidairioil, said noise reducing means comprising ilbrous material inelongated form secured to said airfoil andvhaving loose ends projectingtherefrom, and means for adjusting the exposed lengths of said looseends.

6. In a ilying machine, an airioil, noise reducing means projecting fromthe rear edge oi' said airfoil and extending rearwardly therefrom in ageneral direction oi the airstream, and means .for increasing anddecreasing the distance oi' rearwardextension oi' said noise reducingmeans.

HERBERT L. ADAMS.

